This invention relates to the field of polymerizable monomer compositions which, after polymerization, provide transparent polymeric substrates, and their use for manufacturing optical lenses, more particularly ophthalmic lenses.
Polymerizable compositions have already been disclosed for the manufacture of ophthalmic lenses having a high refractive index.
Compositions comprising a polyoxyalkyleneglycol di(meth)acrylate monomer, a monomer containing a bisphenol-A pattern and leading, through homopolymerization, to a polymer having a higher refractive index than 1.55 and a urethane monomer having 2 to 6 (meth)acrylic end groups are disclosed in EP-A-453,149.
Polymerization is preferably a mixed UV/thermal one.
The patent application EP-745,621 discloses a photopolymerizable composition comprising:
a) 10% to 70% of a bis-2-[(meth)acryloylthioethyl] sulfide or a mixture thereof with the bis [(meth)acryloylthiophenyl]sulfide,
b) 10% to 60% by weight of at least one poly(ethoxy)bisphenol-A di(meth)acrylate type monomer,
c) 5% to 30% by weight of at least one aromatic or polycyclanic mono(meth)acrylate monomer,
d) 0 to 15% by weight of a polyalkyleneglycol di(meth)acrylate, and
e) 0 to 10% by weight of a polythiol.
Patent specification WO 96/38486 discloses polymerizable compositions for the manufacture of optical lenses with a high index and a high Abbe number, comprising 20% to 60% by weight of an acrylate or methacrylate monomer derived from a polycyclic olefin, more particularly a tricyclodecane acrylate or methacrylate derivative, 15% to 60% by weight of a di- or polythiol, 5% to 50% by weight of a divinyl or polyvinyl monomer, and 0 to 20% by weight of a polymerizable comonomer that can be selected amongst methacrylates, acrylates, thiomethacrylates, thioacrylates, vinyls, vinylethers, allyls, epoxides and the like.
The optical items produced from such compositions have high refractive indices up to 1.6 or more and Abbe numbers of 38 or higher.
Although it is mentioned that the polymerizable compositions disclosed in this document can be polymerized thermally and/or by UV radiation, all the embodiments mention a thermal curing step, the time period of which is particularly long (8 hours).
A polymerizable composition for the manufacture of ophthalmic lenses, which comprises 2.5% to 100% of a divinyl ester cyclic monomer, 5% to 30% by weight of a di- or polythiol monomer and, optionally, 1% to 40% by weight of a thiodiacrylate or dimethacrylate monomer, is described in patent specification WO 97/44372.
As it is thus appreciated, numerous polymerizable compositions have been offered in the prior art, leading to materials with a refractive index of 1.6 or higher, without being totally satisfactory in a view to obtaining transparent polymeric substrates, for use in the optical field.
Thus, a first object of this invention aims at providing new polymerizable monomer compositions leading to transparent polymeric substrates.
In particular, the optical substrates must show the following set of features:
a high transparency (transmission being generally higher than 85%, and preferably, higher than or equal to 90%), without or with a very little light diffusion,
a low density lower than 1.4, preferably lower than 1.3, and more preferably lower than 1.2,
a refractive index in the range of 1.55 to 1.60,
a high Abbe number, in the range of 35 to 45, in order to avoid chromatic aberrations,
a lack of colour after polymerization, in particular a low yellow index and a lack of yellowness in the course of time,
a good impact resistance (in particular, the uncoated glass should preferably successfully satisfy the ball fall FDA test),
a good resistance to the action of static stresses,
a good abrasion resistance,
a good ability to several treatments (hard coating deposit, anti-reflection, adhesion and/or anti-shock primers,...), and in particular a good colouration capacity,
a good ability to surfacing and projecting treatments, without the glass global geometry being altered during these operations, and
a low water absorption rate.
A second object of this invention aims at providing compositions that could be easily and rapidly polymerized, in particular they could be polymerized with photopolymerization techniques or mixed photopolymerization and thermal polymerization techniques allowing to reduce the cycle periods for the lens manufacture.
The polymerizable monomer composition according to the invention comprises:
(a) at least 40 parts by weight, preferably at least 50 and more preferably 55 parts by weight of at least one thio(meth)acrylate monomer,
(b) at least one high Abbe number monomer,
(c) at the most 20 parts by weight of an aromatic polyvinyl monomer, and
(d) at least one polythiol, for 100 parts by weight of (a), (b), (c) and (d).
The aromatic polyvinyl monomer typically represents 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight based on 100 parts by weight of (a), (b), (c) and (d).
Preferably, the high Abbe number monomer(s) represent(s) 10 to 40 parts by weight, more preferably 10 to 30, and the polythiol 5 to 20 parts by weight for 100 parts by weight of the mixture of monomers (a), (b), (c) and (d).
Preferably, the polythiol represents at the most 20 parts by weight and more preferably, at the most 15 parts for 100 parts by weight of (a), (b), (c) and (d).
Moreover, the polymerizable compositions may include for 100 parts of the mixture of monomers (a), (b), (c) and (d), up to 30 parts by 35 weight of at least another copolymerizable monomer, different from the monomers of (a), (b), (c) and (d). Preferably, the other polymerizable comonomer represents no more than 20 parts by weight and more preferably, no more than 10 parts by weight for 100 parts of the mixture of monomers of (a), (b), (c) and (d). Preferably, such other copolymerizable monomer is a radical copolymerizable monomer.
One of the advantages of the invention lies in that such compositions may be easily and rapidly photopolymerized.
The monomer or the mixture of monomers for the component (a) of the composition according to the invention encompasses any monomer comprising at least one thioacrylate or thiomethacrylate function.
In the present description and claims, it is understood by a thio(meth)acrylate function a functional group of the formula: 
wherein R1 is H or xe2x80x94CH3.
Preferably, the monomers of the component (a) have the following formula: 
wherein:
R is a linear or branched, monovalent or polyvalent aliphatic hydrocarbon radical, or a monovalent or polyvalent aromatic group, directly linked to the sulfur atom of the thio(meth)acrylate group(s) with an aromatic ring or by means of a linear alkyl chain, said R radical being able to include in its chain one or more groups selected amongst 
R1 is hydrogen or xe2x80x94CH3, and
n is an integer from 1 to 6, preferably from 1 to 3.
The monovalent R radicals may include a linear or branched C1-C5 alkyl group, the radicals of the formula: 
wherein:
R2 and R3 are, independently from one another, H or a linear or branched C1-C5 alkyl radical,
R4 is a linear or branched C1-C5 alkyl radical, a C7-C10aralkyl radical or a C6-C12 aryl radical, optionally substituted, in particular with alkyl and/or halogen groups, and
m is an integer from 1 to 4.
The preferred monovalent R radicals may include: C2H5SCH2CH2xe2x80x94
Monomers of formula (I) in which n=1 and such as defined hereabove, are disclosed, amongst others, in U.S. Pat. No. 4,606,864, JP-63,316,766 and EP-A-0,384,725.
The divalent R radicals which fall within the scope of the monomers of formula (I) may include the linear or branched C2-C10 alkylene radicals that can include in their chain one or more 
groups, the alkylidene radicals of the formula: 
wherein R5 and R6 are C1-C5 alkyl radicals, the radicals of the formula: 
wherein R7 and R8 are linear or branched C1-C5 alkylene groups, that can include one or more 
groups in their chains and X is selected from the C1-C5 alkyl radicals and halogens, and p is an integer from 0 to 4, and the radicals of the formula 
wherein R9 and R10 are linear or branched C1-C5 alkyl radicals, that can include in their chains one or more 
groups and r and s are 0 or 1.
Preferred divalent R radicals may include the radicals:
(CH2)x where x is an integer from 2 to 8,
xe2x80x94(CH2CH2O)yCH2CH2xe2x80x94 radicals where y is an integer from 1 to 4,
xe2x80x94(CH2CH2S)zCH2CH2xe2x80x94 radicals where z is an integer from 1 to 4,
xe2x80x94(CH2)uxe2x80x2(S(CH2)vxe2x80x2)Xxe2x80x2Sxe2x80x94(CH2)wxe2x80x2 radicals where xxe2x80x2 is 0 or 1 and uxe2x80x2, vxe2x80x2, wxe2x80x2 are integers from 2 to 6,
the radicals of the formula: 
wherein u and v are integers from 1 to 4, 
The particularly preferred divalent R radicals are: 
Divalent monomers of the formula (I) are disclosed, inter alia, in EP-A-273,661, EP-A-273,710, EP-A-384,725.
The trivalent R radicals of the monomers of the formula (I) may include C3-C10 alkyltriyl radicals that can include in their chains one or more 
groups, the trivalent alkylaryl radicals the alkyl chains of which can include one or more xe2x80x94Sxe2x80x94 or xe2x80x94Oxe2x80x94 groups, and the trivalent aryl groups.
The trivalent R radicals or higher valency radicals may include: 
etc.
The monomers of formula (I) being recommended in the present invention may include: 
bis[(meth)acryloylthiophenyl]sulfide, where R1 is a hydrogen atom or a methyl group.
The thio(meth)acrylate monomer(s) are preferably selected amongst non aromatic thio(meth)acrylate monomers.
A preferred class of thio(meth)acrylate monomers includes the monomers of the formula: 
wherein Y is a linear or branched C2-C12 alkylene group, a C3-C12 cycloalkylene group, a C6-C14 arylene group or a C7-C26 alkarylene group, where the Y carbon chains can be interrupted by one or more oxygen and/or sulfur atoms and R1 is hydrogen or a methyl group,
the monomers of the formula: 
wherein R1 and Y are defined as above, and n is an integer from 1 to 10, preferably 1 to 6, and the mixtures thereof.
A particularly preferred monomer of the formula (II) has the following formula: 
A particularly preferred monomer of the formula (III) has the following formula: 
In a preferred embodiment of the invention, the component (a) includes a mixture of monomers of formulae (IV) and (V) and optionally a monofunctional monomer of the formula: 
In the preferred mixture, the monomer of formula (IV) represents 10% to 50% by weight, the monomer of formula (V) 30% to 60% by weight and the monomer of formula (VI) 0 to 20% by weight based on the mixture total weight.
The monomers of formulae (II) and (III) are disclosed in U.S. Pat. No. 5,384,379.
The second essential component of the polymerizable monomer compositions according to the invention comprises at least one high Abbe number monomer.
By xe2x80x9chigh Abbe number monomerxe2x80x9d, it is understood a monomer able to generate, through homopolymerization, a transparent polymer with a high Abbe number, i.e. of at least 45, and preferably at least 50.
The high Abbe number monomer preferably comprises at least a non aromatic hydrocarbon cyclic or polycyclic radical.
The high Abbe number monomer is preferably selected amongst at least one of the monomers of the following formulae: 
Where:
Y is a divalent radical selected from xe2x80x94Oxe2x80x94, xe2x80x94CH2xe2x80x94, xe2x80x94C(CH3)2xe2x80x94, xe2x80x94C(H)(CH3)xe2x80x94,
Z is a divalent radical selected amongst xe2x80x94(CH2)p xe2x80x94Oxe2x80x94, p being an integer from 1 to 4, and 
Ra, Rb are H or CH3,
Rc, Rd are, independently from one another, a linear or branched alkyl radical with 1 to 6 carbon atoms,
Ri, Rj are, independently from one another, a linear or branched alkyl radical with 1 to 10 carbon atoms,
wxe2x80x3 is an integer from 1 to 3,
Xxe2x80x3 is an integer from 0 to 3,
yxe2x80x3 is an integer from 0 to 3,
providing xxe2x80x3xe2x88x92yxe2x80x3xe2x89xa71,
kxe2x80x3 is an integer from 0 to 6,
lxe2x80x3 is an integer from 0 to 6,
rxe2x80x3 is an integer from 0 to 6,
sxe2x80x3 is an integer from 0 to 6,
zxe2x80x3 is an integer from 0 to 3, and
txe2x80x3 is an integer from 0 to 3.
The particularly preferred high Abbe number monomers are selected amongst the monomers of the formulae: 
Generally speaking, the preferred high Abbe number monomers are difunctional di(meth)acrylate monomers.
The component (c) is an aromatic polyvinyl monomer or a mixture of aromatic polyvinyl monomers.
In the present invention, the term xe2x80x9cvinylxe2x80x9d is used in the strict sense and does not encompass functions of the acrylic or methacrylic type.
The aromatic polyvinyl monomer may be a monomer of the formula:
[(CH2=CH) (A)axe2x80x2] bxe2x80x2 B
where B is selected amongst: 
A is a divalent chain selected amongst: 
Yxe2x80x2 is a hydrogen atom or an halogen,
axe2x80x2=0, 1 or2,
bxe2x80x2 is an integer from 2 to 6, and
cxe2x80x2 is an integer from 1 to 4.
The preferred aromatic polyvinyl monomers are divinylbenzene, divinylnaphthalene and the derivates thereof, more particularly divinylbenzene.
The polythiol monomers of component (d) of the compositions according to the invention are well known in the art and can be represented with the formula Rxe2x80x2(SH)nxe2x80x2, wherein nxe2x80x2 is an integer of 2 or more, preferably from 2 to 5, and Rxe2x80x2 is an aliphatic, aromatic or heterocyclic radical.
The polythiol compound is preferably a dithiol, trithiol or tetrathiol compound, more particularly a high Abbe number polythiol.
These polythiol compounds are well known in the art and are disclosed, among others, in EP 394,495.
The dithiols useful in the present invention may include 9,10-anthracenedimethanethiol, 1,11-undecanedithiol, 4-ethyl-benzene-1,3-dithiol, 1,2-ethanedithiol, 1,8-octanedithiol, 1,18-octadecanedithiol, 2,5-dichlorobenzene-1,3-dithiol, 1,3-(4-chlorophenyl)propane-2,2-dithiol, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, 1,4-cyclohexanedithiol, 1,1-cycloheptanedithiol, 1,1-cyclopentanedithiol, 4,8-dithioundecane-1,11-dithiol, dithiopentaerythritol, dithiothreitol, 1,3-diphenylpropane-2,2-dithiol, 1,3-dihydroxy-2-propyl-2xe2x80x2,3xe2x80x2-dimercaptopropylether, 2,3-dihydroxypropyl-2xe2x80x2,3xe2x80x2-dimercaptopropylether, 2,6-dimethyloctane-2,6-dithiol, 2,6-dimethyloctane-3,7-dithiol, 2,4-dimethylbenzene-1,3-dithiol, 4,5-dimethylbenzene- 1,3-dithiol, 3,3-dimethylbutane-2,2-dithiol, 2,2- dimethylpropane-1,3-dithiol, 1,3-di(4-methoxy-phenyl)propane-2,2-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 10,11-dimercaptoundecanoic acid, 6,8-dimercapto-octanoic acid, 2,5-dimercapto-1,3,4-thiadiazole, 2,2xe2x80x2-dimercapto-biphenyl, 4,4xe2x80x2-dimercaptobiphenyl, 4,4xe2x80x2-dimercaptobibenzyl, 3,4-dimercaptobutanol, 3,4-dimercaptobutylacetate, 2,3-dimercapto-1- propanol, 1,2-dimercapto-1,3-butanediol, 2,3-dimercaptopropionic acid, 1,2-dimercaptopropylmethylether, 2,3-dimercaptopropyl-2xe2x80x2,3xe2x80x2-dimethoxypropylether, 3,4-thiophenedithiol, 1,10-decanedithiol, 1,12-dodecanedithiol, 3,5,5-trimethyl-hexane-1,1-dithiol, 2,5-toluenedithiol, 3,4-toluenedithiol, 1,4-naphthalenedithiol, 1,5-naphthalenedithiol, 2,6- naphthalenedithiol, 1,9-nonanedithiol, norbornene-2,3-dithiol, bis(2-mercaptoisopropyl)ether, bis(11-mercaptoundecyl)sulfide, bis(2-mercaptoethyl)ether, bis(2-mercaptoethyl)sulfide, bis (18-mercatooctadecyl)sulfide, bis(8-mercaptooctyl)sulfide, bis(12-mercaptodecyl)sulfide, bis(9-mercaptononyl)sulfide, bis(4-mercaptobutyl)sulfide, bis(3-mercaptopropyl)ether, bis(3-mercaptopropyl)sulfide, bis(6-mercaptohexyl)sulfide, bis(7-mercaptoheptyl)sulfide, bis(5-mercaptopentyl)sulfide, 2,2xe2x80x2-bis(mercaptomethyl)acetic acid, 1,1-bis(mercaptomethyl)cyclohexane, bis(mercaptomethyl)durene, phenylmethane-1,1-dithiol, 1,2-butane-dithiol, 1,4-butanedithiol, 2,3-butanedithiol, 2,2-butanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 2,2-propanedithiol, 1,2-hexanedithiol, 1,6-hexanedithiol, 2,5-hexanedithiol, 1,7-heptanedithiol, 2,6-heptanedithiol, 1,5-pentanedithiol, 2,4-pentanedithiol, 3,3-pentanedithiol, 7,8-heptadecanedithiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, 2-methylcyclohexane-1,1-dithiol, 2-methylbutane-2,3-dithiol, ethyleneglycol dithioglycolate, ethylene glycol bis(3-mercaptopropionate). The trithiols may include 1,2,3-propanetrithiol, 1,2,4-butanetrithiol, trimethylolpropanetrithiol glycolate, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol trithioglycolate, pentaerythritol tris(3-mercaptopropionate), 1,3,5-benzenetrithiol and 2,4,6-mesitylenetrithiol.
The polythiols useful in the compositions of the present invention may further include neopentane tetrathiol, 2,2xe2x80x2-bis-(mercaptomethyl)-1,3-propanedithiol, pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (thioglycolate), 1,3,5-benzenetrithiol, 2,4,6-toluenetrithiol, 2,4,6-methylenetrithiol and the polythiols of the following formulae: 
(HS CH2CH2 COO CH2)3 C C2H5 (TTMP), and 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol.
The preferred polythiols according to the present invention are ethyleneglycol bis(thioglycolate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis thiopropionate (PETP), 4- mercaptomethyl-3,6-dithia-1,8-octanedithiol (MDO), bis(2-mercaptoethyl)sulfide (DMDS) and pentaerythritol tetrakis thioglycolate (PETG).
As previously indicated, besides the monomers of components (a), (b), (c) and (d), the compositions according to the invention may include other copolymerizable monomers, particularly radical copolymerizable monomers.
Such monomers make it possible to match the properties of the resulting transparent substrates.
These monomers may be present in the compositions of the invention in a proportion of 0 to 30% based on the total weight of the monomers of components (a), (b), (c) and (d), preferably 0 to 20% and more preferably 0 to 10%.
Such monomers may include:
alkyl(meth)acrylates such as methyl(meth)acrylate and ethyl(meth)acrylate, cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and dicyclopentyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, naphthyl (meth)acrylates, phenoxyalkyl (meth)acrylates such as phenoxyethyl (meth)acrylate and phenoxybutyl (meth)acrylate, alkyleneglycol di(meth)acrylates such as ethyleneglycol di(meth)acrylate and propyleneglycol di(meth)acrylate, polyalkyleneglycol di(meth)acrylates such as polyethyleneglycol di(meth)acrylates and polybutyleneglycol di(meth)acrylates, neopentylglycol di(meth)acrylate and the derivates of bisphenol-A di(meth)acrylates, poly(meth)acrylate urethanes.
The bisphenol-A di(meth)acrylates compounds may include the compounds of the formula: 
wherein R5 is H or CH3 and n1+n2 has a mean value in the range of 0 to 40.
Preferred compounds having the above-mentioned formula are those for which R5=CH3 and {overscore (n5+n2)}=2,6 (EBADMA), {overscore (n1+n2)}=4 (DBADMA), {overscore (n1+n2)}=10 (OBADMA) and {overscore (n1+n2)}=30.
The polymerizable compositions according to the invention may also include conventionally used additives in polymerizable compositions for moulding optical items, more particularly spectacle glasses, in the conventional proportions, namely inhibitors, dyes, UV absorbers, perfumes, deodorants, antioxidants and anti-yellowing additives.
More particularly, the anti-yellowing agents such as those disclosed in the U.S. Pat. Nos. nxc2x0 5,442,022, 5,545,828, 5,702,825 and 5,741,831 may be used.
The preferred anti-yellowing agent is 3-methyl 2-butene 1-ol (MBOL).
Triphenylphosphine (TPP) and Irganox(copyright) 1010 (pentaerythritol-tetrakis[3(3,5-di-tert.-butyl-4-hydroxyphenyl)propionate] (CG 1010) may be mentioned as preferred examples of antioxidant agents.
Perfumes make it possible to hide the smell from the compositions, more particularly in surfacing operations.
The compositions according to the invention generally include polymerization initiators, preferably photoinitiators or mixtures of photoinitiators and thermal initiators, in a proportion of 0.001% to 5% by weight based on the total weight of the polymerizable monomers present in the composition.
The photoinitiators useful in the polymerizable compositions according to the invention may include more particularly 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide (TPO), 1-hydroxycyclo-hexylphenylketone, 2,2-dimethoxy-1,2-diphenylethane 1-one, alkylbenzoylethers, the commercially available photoinitiator from Ciba-Geigy Corporation under the tradename CGI 1700, which is a 25/75 mixture of a compound of the formula: 
and a compound of the formula: 
and the CGI 1850 photoinitiator commercially available from Ciba Geigy Corporation, which is a 50/50 mixture (by weight) of compound A and Irgacure(copyright) 184 of the formula: 
Another preferred photoinitiator is CGI 819 from Ciba Geigy Corporation of the formula: 
Other photoinitiators of the same type may also be used, such as that of the formula: 
As previously mentioned, the preferred polymerizable compositions according to the invention are photopolymerizable compositions comprising one or more photoinitiators.
Still preferably, the polymerizable compositions according to the invention are photo- and thermopolymerizable compositions including both a polymerization photoinitiator and a polymerization thermal initiator.
The thermal polymerization initiators are compounds which are well known in the art and may include peroxides, such as benzoyl peroxide, cyclohexyl peroxydicarbonate, isopropyl peroxydicarbonate and tert-butylperoxy(2-ethyl hexanoate).
The present invention will now be described more in details in the following examples. In such examples, unless otherwise mentioned, all the percentages and parts are expressed in weight.